Glenoid implant for a shoulder prosthesis, and surgical kit

ABSTRACT

A glenoid implant for a shoulder prosthesis for implantation in the glenoid of a scapula according to embodiments of the present invention includes a central fixation element; an articular body configured for articulation with a humerus, the articular body comprising a plate, the plate comprising a side configured to be oriented toward the glenoid, the side comprising a central protrusion, wherein the central fixation element comprises a means for mechanically engaging with the central protrusion; a first means for locking rotation of the central fixation element with respect to the glenoid; and a second means for locking rotation of the articular body with respect to the glenoid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/363,159, filed Jan. 31, 2012, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/438,570, filed on Feb. 1,2011, and claims foreign priority to French Patent Application No.20110050994, filed on Feb. 8, 2011, both of which are incorporatedherein by reference in their entireties for all purposes.

TECHNICAL FIELD

Embodiments of the present invention relate generally to a glenoidimplant for a shoulder prosthesis, as well as a surgical kit comprisingsuch a glenoid implant.

BACKGROUND

Typically, a shoulder prosthesis includes a glenoid implant intended toreplace the glenoid cavity of the scapula and/or a humeral implantintended to replace the humeral head. The glenoid implant generallyincludes an articular body intended to articulate with the humeral head,and a fixation means to stabilize the articular body with respect to thescapula.

SUMMARY

A glenoid implant for a shoulder prosthesis for implantation in theglenoid of a scapula according to embodiments of the present inventionincludes a central fixation element, an articular body configured forarticulation with a humerus, the articular body including a plate, theplate including a side configured to be oriented toward the glenoid, theside including a central protrusion, wherein the central fixationelement includes a means for mechanically engaging with the centralprotrusion, a first means for locking rotation of the central fixationelement with respect to the glenoid, and a second means for lockingrotation of the articular body with respect to the glenoid.

A glenoid implant according to embodiments of the present inventionincludes a central fixation element, an articular body configured forarticulation with a humerus, the articular body including a centralprotrusion, wherein the central fixation element and the centralprotrusion are configured for mechanical interengagement, a firstlocking mechanism configured to lock rotation of the central fixationelement with respect to the glenoid, and a second locking mechanismconfigured to lock rotation of the articular body with respect to theglenoid.

A method for implanting a glenoid implant according to embodiments ofthe present invention includes implanting a central fixation elementinto the glenoid, mechanically engaging a central protrusion of anarticular body with the central fixation element, locking rotation ofthe central protrusion with respect to the central fixation element, andlocking rotation of the articular body with respect to the glenoid.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a glenoid implant according toembodiments of the present invention.

FIG. 2 illustrates a front axial cross-sectional view of the glenoidimplant of FIG. 1, according to embodiments of the present invention.

FIG. 3 illustrates a front axial cross-sectional view of a centralfixation element of the glenoid implant of FIG. 1, according toembodiments of the present invention.

FIG. 4 illustrates a front elevation view of an articular body of theglenoid implant of FIG. 1, according to embodiments of the presentinvention.

FIG. 5 illustrates a perspective view of a glenoid implant according toanother embodiment of the present invention.

FIG. 6 illustrates an axial cross-sectional view of the glenoid implantof FIG. 5, according to embodiments of the present invention.

FIG. 7 illustrates an axial cross-sectional view of a central fixationelement of the glenoid implant of FIG. 5, according to embodiments ofthe present invention.

FIG. 8 illustrates a perspective view of an articular body of theglenoid implant of FIG. 5, according to embodiments of the presentinvention.

FIG. 9 illustrates an exploded perspective view of a glenoid implantaccording to another embodiment of the present invention.

FIG. 10 illustrates a perspective axial cross-sectional view of theglenoid implant of FIG. 9, according to embodiments of the presentinvention.

FIG. 11 illustrates an exploded perspective view of a glenoid implantaccording to another embodiment of the present invention.

FIG. 12 illustrates a perspective axial cross-sectional view of theglenoid implant of FIG. 11, according to embodiments of the presentinvention.

FIG. 13 illustrates a perspective axial cross-sectional view of theglenoid implant of FIG. 9 with the articular body of the glenoid implantof FIG. 11 superimposed thereon, according to embodiments of the presentinvention.

FIG. 14 illustrates an axial cross-sectional view of the glenoid implantof FIG. 9 with the articular body of the glenoid implant of FIG. 11superimposed thereon, according to embodiments of the present invention.

FIG. 15 illustrates an exploded perspective view of a glenoid implantaccording to another embodiment of the present invention.

FIG. 16 illustrates a perspective axial cross-sectional view of theglenoid implant of FIG. 15, according to embodiments of the presentinvention.

FIG. 17 illustrates a perspective view of a glenoid implant according toanother embodiment of the present invention.

FIG. 18 illustrates a an axial cross-sectional view of the glenoidimplant of FIG. 17, according to embodiments of the present invention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1-4 show a glenoid implant 1, referred to as anatomical (or notreversed), configured to be implanted in the glenoid of a scapula (orshoulder blade, not shown), of a human being. The glenoid implant 1includes an articular body 2, a central fixation element 3 for anchoringthe articular body 2 in the scapular glenoid, and a locking screw 4configured to deter rotation of the central element 3 with respect tothe scapula, according to embodiments of the present invention. Thearticular body 2, after having been implanted in the glenoid, isconfigured to articulate with a head, eventually a prosthetic head, of ahumerus (not shown) of the patient, in order to reproduce articularperformance as close as possible to the original performance of thepatient's shoulder.

As used herein, the terms “superior” and “inferior” are used to refer tothe orientation of the glenoid implant as shown in FIG. 1, in which thearticular body 2 is toward a top of a longitudinal geometric axisX1-X′1, and the screw 4 is toward a bottom of the axis X1-X′1, accordingto embodiments of the present invention. In other words, an element islocated superior to another element if it is closer to X1 than the otherelement, and an element is inferior to another element if it is closerto X′1 than the other element. As used herein, the term “tronconical” isused to refer to a shape or surface that is or is like a truncated coneshape or surface.

The articular body 2, which is shown by itself in FIG. 4, includes aplate 21 that is substantially perpendicular to the longitudinalgeometric axis X2-X′2 of the articular body. The plate 21 defines asuperior surface 22 that is concave, which constitutes an articularsurface for the articulation of the scapula with the humeral head, andby an inferior surface 23, provided with a central protrusion 24, whichextends along the axis X2-X′2. The central protrusion 24 includes asuperior portion 24.1 which is cylindrical with a circularcross-section, an intermediate portion 24.2 which is cylindrical with acircular cross-section that is smaller in diameter than that of thesuperior portion 24.1, and an inferior portion 24.3 that is tronconicaland of which the diameter becomes smaller as it extends further from theplate 21, according to embodiments of the present invention. Theintermediate portion 24.2 is provided with five fins 25 perpendicular tothe axis X2-X′2 and parallel to each other, which are separated alongthe length of the central portion 24.2 and each of which extends aboutthe perimeter of the intermediate portion 24.2, according to embodimentsof the present invention.

The articular body 2 is formed of one or two synthetic materials, suchas, for example, polyethylene, polyether ether ketone (“PEEK”), orpolyurethane, which gives the fins 25 an elasticity to permit them todeform slightly.

The inferior surface 23 is also provided with a lateral post 26 whichextends along a direction that is parallel to the axis X2-X′, accordingto embodiments of the present invention. The lateral post 26 includes asuperior portion 26.1 which is connected to the inferior surface 23 ofthe plate 21, and an inferior portion 26.2 connected to the superiorportion 26.1. The superior portion 26.1 is cylindrical with a circularcross-section, and its diameter is smaller than the diameter of thecentral protrusion 24. The inferior portion 26.2 is tronconical, and itsdiameter increases as it extends further from the plate 21, according toembodiments of the present invention.

The central fixation element 3, shown in more detail in FIG. 3, isgenerally formed as a hollow cylinder of circular cross section, with alongitudinal geometric axis X3-X′3. The central element 3 is defined byan external lateral surface 31 which includes a self-tapping thread, andis traversed longitudinally by an opening 32, centered about thelongitudinal axis X3-X′3, which extends between a superior end 33 and aninferior end 34 of the central element 3, according to embodiments ofthe present invention. The inferior end 34 is tronconical and itsdiameter becomes smaller as it approaches the inferior end 34, accordingto embodiments of the present invention.

The opening 32 includes a superior portion 32.1 that is cylindrical witha circular cross section, a tapping portion 32.2 of a diameter similarto the superior portion 32.1, a tool receptacle portion 32.3 with ahexagonal transversal cross section, and an inferior portion 32.4 thatis cylindrical with a circular cross section and that is tapped and hasa smaller diameter than the superior portion 32.1, according toembodiments of the present invention.

The central element 3 is made from a metal alloy or biocompatibleceramic, and its rigidity is higher than that of the articular body 2.For example, the central element 3 can be made from stainless steel,titanium, titanium alloy, cobalt-chrome alloy, and/or PEEK. The centralelement 3 is constructed so as to not deform in use.

The maximum transversal area of the central element 3, takenperpendicularly to the longitudinal axis X3-X′3, is smaller than theminimal transversal area of the plate 21 of the articular body 2, takenperpendicularly to the longitudinal axis X2-X′2. The portion of thelargest section of the central element 3 is the superior threadedportion.

The contact between the central element 3 and the articular body 2occurs only along a portion of the articular body 2, for example alongthe central protrusion 24, according to embodiments of the presentinvention. The central element 3 is not in contact with the entirety ofthe inferior surface 23 of the plate 21, according to embodiments of thepresent invention.

According to some embodiments of the present invention, the plate 21 is1.8 to 5 times larger at its maximum transversal section than thecentral element 3. According to some embodiments of the presentinvention, the plate is 2.2 times larger at its maximum transversalsection than the central element 3.

The central element 3 ensures anchoring of the articular body 2 in theglenoid via the central protrusion 24, but the central element 3 doesnot directly support the plate 21, according to embodiments of thepresent invention.

The screw 4, with a longitudinal geometric axis X4-X′4, includes a head41 and a stem 44 that includes self-tapping threads, according toembodiments of the present invention. A blind hole 42 of hexagonalcross-section, centered on the axis X4-X′4, is formed in the head 41 ofthe screw 4. An external lateral surface 43 of the head 41 is threaded,and towards the top of the head 41 is a collar 45 with a larger diameterthan the threaded portion 43. The screw 4 is made from a metallicmaterial or biocompatible ceramic, such as a stainless steel, titanium,titanium alloy, and/or cobalt-chromium alloy, according to embodimentsof the present invention.

As used herein, a threading or self-tapping thread is “to the right”when the driving action is performed with counterclockwise rotation, andis “to the left” when the driving action is performed with clockwiserotation. The threading of the lateral external surface 31 of thecentral element 3 is to the right, as shown by the arrow F3. Thethreading of the stem 44 of the screw 4 is to the left, as shown by thearrow F44, and the threading of the head 41 of the screw 4 and theself-tapping of the inferior portion 32.4 of the opening 32 are to theright, as shown by the arrow F41, according to embodiments of thepresent invention.

As the surgeon positions the glenoid implant 1 in the glenoid of thescapula, the surgeon first pierces a hole in the glenoid, of a diameterslightly smaller than the external diameter of the central element 3.Then, the surgeon screws the central element 3 into the glenoid, using atool (not shown) equipped with a tip of hexagonal cross section which isinserted in the tool receptacle 32.3 of opening 32. The self-tappingthreads of the central element 3 permit it to penetrate into theglenoid, more precisely into the preformed hole formed by the surgeon,while tapping it. The central element 3 permits by itself the fixationof the articular body 2 in the glenoid, according to embodiments of thepresent invention.

Next, the surgeon makes a hole in the glenoid, of a diameter slightlysmaller than the diameter of the stem 44 of the screw 4, in passing thebit of a surgical drill through the opening 32 of the central element 3.The drill bit is guided by a tool (not shown) which permits passage ofthe drill bit through the bottom of the central element 3 while alsoprotecting the threading 32.4 on the inside of the central element 3,according to embodiments of the present invention. The surgeon thenslides or drives the head 41 of the screw 4 into the hole, with the helpof a tool (not shown) equipped with a hexagonal tip which inserts intothe blind hole 42 in the screw 4, according to embodiments of thepresent invention. The threading of the head 41 of the screw 4cooperates with the threading of the inferior portion 32.4 of theopening 32. The axis X3-X′3 of the central element 3 is thensubstantially in alignment with the axis X4-X′4 of the screw 4. Thethreading of the head 41 is in the same direction as the threading ofthe stem 44 of the screw 4, which permits the surgeon, in the samemovement, to screw the head 41 in the inferior portion 32.4 and to crewthe stem 44 of the screw 4 into the hole which has been formed in theglenoid. The self-tapping threads of the stem 44 of the screw improvethe anchoring of the screw 4 in the glenoid. Once in place, the collar45 of the head 41 of the screw 4, which has a larger diameter than theinferior portion 32.4 of the opening 32, permits the retention of thehead 41 in the opening 32 and prevents its passage through the opening32.

According to one alternative embodiment, the threading of the head 41 ofthe screw 4 includes two threads, to facilitate the acceptance of thethreading in the tapping of the inferior portion 32.4 of the opening 32.The pitch of the threading of the head 41 may be equal to the pitch ofthe threading of the stem 44 of the screw 4 to optimize the penetrationof the screw 4 in the glenoid while the threading of the head 41cooperates with the tapping of the inferior portion 32.4 of the opening32, according to embodiments of the present invention.

The threading of the head 41 may also include a stop or a brake, such asfor example a transverse pin of synthetic material, for preventing aloosening or disengagement of the screw, according to embodiments of thepresent invention.

Once the central element 3 and the screw 4 are placed in the glenoid,the sub-assembly formed by these two elements is locked in rotation,with respect to the glenoid, about the axes X3-X′3 and X4-X′4, due tothe opposed directions of the threading of the stem 44 of the screw 4.In fact, when the subassembly tends to unscrew in the direction of thethreading of the external lateral surface 31 of the central element 3,the rotation is locked by the threading of the stem 44 of the screw 4.On the other hand, when the subassembly tends to unscrew in thedirection of the threading of the stem 44 of the screw 4, the rotationis locked by the threading of the external lateral surface 31 of thecentral element 3, according to embodiments of the present invention.

Before or after having placed the central element 3 and the screw 4, thesurgeon pierces a lateral hole in the glenoid, adapted to receive thelateral post 26 of the articular body 2, according to embodiments of thepresent invention.

Once the central element 2 and the screw 4 are in place in the glenoid,the surgeon pushes in the central protrusion of the articular body 2into the opening 32 of the central element 3, until the interior surface23 of the plate 21 comes into contact against the superior end 33 of thecentral element. The axes X2-X′2, X3-X′3, and X4-X′4 are then coincidentand overlapping with the axis X1-X′1 of the glenoid implant 1, accordingto embodiments of the present invention.

According to an alternative embodiment of the present invention, thesurgeon pushes the central protrusion 24 into the opening 32 until theinferior side 23 of the plate 1 comes into contact against the glenoid,without the inferior side 23 being in contact with the superior end 33of the central element. This can limit the wear of the articular body 2against the central element 3, according to embodiments of the presentinvention.

The superior portion 24.1 of the central protrusion 24 is thus lodged inthe superior portion 32.1 of the opening 32, and the intermediateportion 24.2 of the central portion 24 is thus lodged in the threads ofthe threaded portion 32.2 of the opening 32, and the fins 25 are thusretained between the threads through a complementarity of shapes andflexible deformation. The lateral post 26 becomes trapped in thecorresponding hole formed in the glenoid, and prevents rotation of thearticular body 2 about the axis X1-X′1 with respect to the glenoid,according to embodiments of the present invention.

The fins 25 prevent translation of the articular body 2, along thelength of the axis X1-X′1, with respect to the central element 3, aslong as the strength of the forces which are applied to the glenoidimplant 1 do not surpass too significantly the strength of the forcesundergone by the natural articulation of the shoulder.

Once the glenoid implant 1 is implanted in the glenoid, its rotationabout the axis X1-X′1 with respect to the glenoid is locked. In fact,the lateral post 26 locks the rotation of the articular body 2 withrespect to the glenoid, and the rotation, with respect to the glenoid,of the subassembly formed by the central element 3 and the screw 4, islocked due to the threading pitch being in a direction different fromthe central element 3 and the shaft 44 of the screw 4, according toembodiments of the present invention.

The locking of the rotation of the glenoid implant 1 with respect to theglenoid is effective, as it prevents the glenoid implant 1 fromdisengaging under the action of the mechanical forces resulting from thepressure and movements of the humeral head against the superior side 22of the articular body 2.

The lateral post 26, which permits the locking of the articular body 2in rotation about the axis X1-X′1 with respect to the glenoid, isoptional and may be substituted for other rotational locking mechanisms,according to embodiments of the present invention. For example, thesuperior end of the external lateral surface of the central post 24 mayextend superiorly of the central element 3, and its transversal crosssection may be, for example, square or hexagonal, so as to lock therotation of the articular body 2 with respect to the glenoid, once thecentral element 3 is placed into the glenoid, according to embodimentsof the present invention. In such case, the surgeon prepares a solecavity in the glenoid, composed of a portion for receiving the centralelement 3, aligned with a portion to receive the screw 4. Such aconfiguration may be particularly helpful as the bony tissue is thus inlarge part preserved.

FIGS. 5 to 8 illustrate another embodiment of a glenoid implant 101,which includes elements generally similar to elements described withrespect to glenoid implant 1, augmented by 100.

Also, the glenoid implant 101, with longitudinal axis X101-X′101,includes an articular body 102 with a metal back, a central fixationelement 103 for anchoring in the articular body 102 in the glenoid of ascapula, and a screw 104 for locking rotation of the central element 103with respect to the scapula, according to embodiments of the presentinvention.

The articular body 102, shown from a bottom perspective view in FIG. 8,includes a plate 121 with a circular cross-sectional shape,perpendicular to a longitudinal axis X102-X′102 of the articular body102. The plate 121 is defined by a superior side 122 and by an inferiorside 123. An external lateral surface 126 of the plate 121 may betronconical, according to embodiments of the present invention.

The superior side may be configured to receive a supplemental piece (notshown) adapted to articulate with the humerus. In the case of a reversedprosthesis, this supplemental piece is hemispherical, and an implantwhich includes a concave articular surface may be implanted in thehumerus.

Four receptacles 121 a, 121 b, 121 c and 121 d in the form of truncatedspheres are formed in the plate 121 and open toward both the superiorside 122 and the inferior side 123, according to embodiments of thepresent invention.

Two inserts 105 include a spherical external surface and are received inthe receptacles 121 b and 121 d. The inserts 105 are in rotationalengagement with the articular body 102, according to embodiments of thepresent invention. The inserts 105 are each traversed by a threaded holeadapted to receive a screw 106. The screws 106 are represented by theiraxes 106 shown in FIG. 6.

The inferior side 123 of the plate 121 is provided with a centralprotrusion 124, with a longitudinal axis X102-X′102, which includes asuperior portion 124.1 that is cylindrical with a circularcross-sectional shape, connected to the inferior side 123, and aninferior portion 124.2 that is tronconical, the diameter of whichbecomes smaller further from the plate 121.

The articular body 102 is traversed longitudinally by an opening 125,centered on the axis X102-X′102, which includes a superior threadedportion 125.1, and an inferior portion 125.2 with a circularcross-sectional shape. The threading of the superior portion 125.1 isconfigured to permit fixation to the articular body 102 of asupplemental piece adapted to articulate with the humeral head.

The articular body 102 is metallic and/or ceramic, according toembodiments of the present invention. For example, the articular body102 may be made from stainless steel, titanium, an alloy of titanium,and/or an alloy of cobalt-chromium, according to embodiments of thepresent invention.

The central element 103, shown in more detail in FIG. 7, is generallyformed as a cylinder with a circular cross-sectional shape, with alongitudinal axis X103-X′103. The central element 13 is defined by alateral external surface 131 which includes a self-tapping thread, andis traversed longitudinally by an opening 132 which extends between asuperior end 133 and an inferior end 134 of the central element 103. Theinferior end 134 of the central element 3 is tronconical and itsdiameter gets smaller as it gets closer to the inferior end 134,according to embodiments of the present invention.

The opening 132 includes a superior portion 132.1 which is cylindrical,with a circular cross-sectional shape, a tronconical portion 132.2, ofwhich the diameter gets smaller as it approaches the inferior end 134, ahexagonal portion 132.3, of which the transverse cross-sectional shapeis a hexagon, a rounded part 132.4 in the form of a dome, of which thesummit is oriented toward the bottom, and an inferior portion 132.5which is cylindrical with a circular cross-sectional shape, according toembodiments of the present invention.

The central element 103 is metallic and ceramic, according toembodiments of the present invention. For example, the central element103 may be formed of or made with stainless steel, titanium, titaniumalloy, and/or cobalt-chrome alloy, according to embodiments of thepresent invention.

The maximum transverse cross-sectional dimension of the central element103, taken perpendicularly to the longitudinal axis X103-X′103, issmaller than the transverse cross-sectional dimension of the plate 121of the articular body 102, taken perpendicularly to the longitudinalaxis X102-X′102. The maximum transverse cross-sectional dimension of thecentral element 103 is located at the level of the superior end 133,according to embodiments of the present invention. The contact betweenthe central element 103 and the articular body 102 is made solelybetween a portion of the articular body 102, for example the centralprotrusion 124, and an annular zone of the inferior surface 123surrounding the central protrusion 124, according to embodiments of thepresent invention. The central element 103 is not in contact with theentirety of the inferior surface 123 of the plate 121, according toembodiments of the present invention. The annular zone of pressure ofthe plate 121 on the central element 3 is relatively small with respectto the overall dimensions of the inferior surface 123, according toembodiments of the present invention.

The central element 103 ensures the anchoring of the articular body 102in the glenoid, and the element central 103 does not support the plate121, according to embodiments of the present invention.

The screw 104, having a longitudinal axis X104-X′104, includes a head141 and a threaded stem 144 which may also be self-tapping, according toembodiments of the present invention. A blind hole 142 of squarecross-sectional shape, centered on the longitudinal axis X104-X′104, isformed in the head 141 of the screw 104, according to embodiments of thepresent invention. A lateral external surface 13 of the head 141 isformed of a dome of which the summit is turned toward the bottom and ofwhich the geometry is complementary to that of the rounded portion 132.4of the opening 132 of the central element 103, according to embodimentsof the present invention.

The screw 104 is metallic or ceramic, according to embodiments of thepresent invention. For example, the screw 104 may be formed fromstainless steel, titanium, titanium alloy, and/or cobalt-chrome,according to embodiments of the present invention.

The threading of the external lateral surface 131 of the central element103 is to the right, as shown by the arrow F131, while the threading ofthe stem 144 of the screw 104 is to the left, as shown by the arrowF144, according to embodiments of the present invention.

When the surgeon has achieved the placement of the glenoid implant 101in the glenoid, the surgeon first forms a hole in the glenoid, of adiameter slightly smaller than the external diameter of the centralelement 103. Then, the surgeon inserts the central element 03 into theglenoid, for example with a tool (not shown), equipped with a hexagonaltip which is inserted into the hexagonal portion 132.3, according toembodiments of the present invention. The self-tapping threading of thecentral element 103 permits it to penetrate in the glenoid while alsotapping. The surgeon makes a hole in the glenoid, of a diameter that isslightly smaller than the diameter of the stem 144 of the screw 104, inpassing a drill bit (not shown) through the opening 132 of the centralelement 103. The drill bit is guided by a tool (not shown) which fitsinto one of the portions of the opening 132, according to embodiments ofthe present invention. The surgeon then inserts the screw 104 into thehole which has been formed, with the help of a tool (not shown) equippedwith a square tip which is inserted into the blind hole 142 of the screw104. Finally, the lateral external surface 141 of the screw 104 is incontact with the lateral surface of the portion 132.4 of the opening ofthe central element 103, according to embodiments of the presentinvention.

Once the central element 103 and the screw 104 are implanted in theglenoid, the sub-assembly formed by these two elements is locked inrotation, with respect to the glenoid, due to the opposed directions ofthe threading of the external surface 131 of the central element 103,with respect to the threading direction of the stem 144 of the screw104, according to embodiments of the present invention.

Once the central element 103 and the screw 1034 are in place in theglenoid, the surgeon pushes in the central protrusion 124 of thearticular body 102 into the opening 132 of the central element 103,until the tronconical portion of the interior surface 124.2 of thecentral protrusion 124 is coincident with the tronconical portion 132.2of the opening 132. Such an assembly of a “Morse cone” permits thelocking of the translation and the rotation of the articular body 102with respect to the central element 103, as long as the strength of theforces which are applied thereto do not exceed the forces undergone by anatural articulation, according to embodiments of the present invention.

Also, if the surgeon removes the glenoid implant 101 from the scapula,the articular body 102 may be uncoupled from the central element 103with appropriate tools, according to embodiments of the presentinvention.

The screws 106 are adapted to fix in a more stable manner the articularbody 102 to the glenoid to lock as well the rotation of the articularbody 102 with respect to the glenoid. The rotation of the inserts 105 inthe receptacles 121 b and 121 d permits the screws 106 to be oriented inthe desired manner and direction.

The articular body 106 may be fixed to the central element 103 prior toinsertion of the screw 104 or before the insertion of the centralelement 103 into the glenoid, according to embodiments of the presentinvention.

Finally, the surgeon couples to the articular body 102 a supplementalpiece adapted to articulate with the humeral head. This supplementalpiece is inserted into the threading of the superior portion 125.1 ofthe receptacle 125. The supplemental piece includes a tronconical hollowadapted to mate with the lateral surface 126 of the plate 121, accordingto embodiments of the present invention.

FIGS. 9-10 illustrate a glenoid implant 201 according to anotherembodiment of the present invention, of which the elements similar toglenoid implant 1 carry the same reference numbers, augmented by 200.

The glenoid implant 201, with a longitudinal axis X201-X′201, alsoincludes an articular body 202, for example of the “metal back” type,and a central element 203 for anchoring the articular body 202 into theglenoid of a scapula, according to embodiments of the present invention.

The articular body 202, with a longitudinal axis X202-X′202, includes acircular plate 221 which is perpendicular to the axis X202-X′202, whichis defined by a superior side 222 and an inferior side 223. The plate221 of the articular body 202 also includes a lateral surface 226. Theinferior side 223 includes a central protrusion 224 which is cylindricalwith a circular cross-sectional shape, centered on the axis X202-X′202.The central protrusion 224 is hollow and defines a tronconicalreceptacle 225, of which the diameter becomes smaller as it approachesthe plate 221.

The superior side 222 of the plate 221 is adapted to receive asupplemental piece (not shown), configured to articulate with thehumeral head.

The central element 203, with a longitudinal axis X203-X′203, includes atronconical intermediate portion 203.2 with a diameter which getssmaller between a superior end 233 and an inferior end 234 of thecentral element 203. A lateral external surface 231 of the intermediateportion 203.2 includes a self-tapping threading and is traversedtransversally by holes 238. The intermediate portion 203.2 includes nearits bottom an inferior tronconical portion 203.3, which has a cone shapethat is sloped at a greater angle with respect to the longitudinal axisX203-X′203 than the cone shape of the intermediate portion 203.2. Theintermediate portion 203.2 includes near its top a tronconical superiorportion 203.1, of which the diameter diminishes as it approaches thesuperior end 233, according to embodiments of the present invention. Aperipheral groove 237 is defined between the intermediate portion 203.2and the superior portion 203.1, according to embodiments of the presentinvention.

The central element 203 is traversed by a longitudinal opening 232,centered on the axis X203-X′203, which opens on both ends of the centralelement 203. The opening 232 includes a superior portion 232.1, with ahexagonal cross-sectional shape, and an inferior portion 232.2 which iscylindrical with a circular cross-sectional shape and which connects thesuperior portion 232.1 to the inferior end 234 of the central element203, according to embodiments of the present invention.

The holes 238 are spaced or set off from one another along theintermediate portion 203.2 and open from the inferior portion 232.2 ofthe opening 232, according to embodiments of the present invention.

The maximum transverse cross-sectional dimension of the central element203, taken perpendicularly to the longitudinal axis X203-X′203, issmaller than the transverse cross-sectional dimension of the plate 221of the articular body 202, taken perpendicularly to the longitudinalaxis X202-X′202. The contact between the central element 203 and thearticular body 202 occurs solely along a portion of the articular body202, for example on the central protrusion 224. The central element 203is not in contact with the entirety of the inferior surface 223 of theplate 221. The central element 203 helps to ensure anchoring of thearticular body 202 in the glenoid, and the central element 203 does notsupport the inferior surface 223 of the plate 221, according toembodiments of the present invention.

When placing the glenoid implant 201 in the scapula, the surgeon firstforms a hole in the glenoid, with a diameter slightly smaller than thediameter of the central element. Next, the surgeon inserts the centralelement 203 into the glenoid, using a tool (not shown) equipped with ahexagonal tip which is inserted into the superior portion 232.1 of theopening 232, according to embodiments of the present invention.

The articular body 202 is assembled to the central element 203 injoining the central protrusion 224 to the superior portion 203.1 of thecentral element 203. When the articular body 202 is assembled to thecentral element 203, the articular body 202 is locked in translation andin rotation with respect to the central element 203, due to the fixationof the “Morse cone” type between the two elements.

Once the glenoid implant is implanted, the bony tissue of the glenoidcolonizes the holes 238, which contributes to the locking of therotation of the central element 203 with respect to the glenoid, andimproves the longevity of the glenoid implant 201. The rotation of thearticular body 202 with respect to the glenoid is locked via the screwand the inserts (not shown), similar to screws 106 and inserts 105,according to embodiments of the present invention.

FIGS. 11 to 12 illustrate a glenoid implant 301, according to anotherembodiment of the present invention, of which the elements similar toimplant 1 have the same reference numbers augmented by 300.

The glenoid implant 301, with longitudinal axis X301-X′301, includes anarticular body 302 and a central element 303 for anchoring the articularbody 302 in the glenoid of a scapula, according to embodiments of thepresent invention.

The articular body 302, after its fixation to the glenoid, is adapted toarticulate with a head, eventually a prosthetic head, of a humerus (notshown), of the patient with a view to reproducing an articularperformance as close as possible to the performance of the patient'soriginal shoulder, according to embodiments of the present invention.

The articular body 302, with a longitudinal axis X302-X′302, includes aplate 321, generally perpendicular to the axis X302-X′302, defined by asuperior side 322 and an inferior side 323. The superior side 322includes an articular surface for articulation of the scapula with ahumeral head. The interior face 323 of the plate 321 includes a centralprotrusion 324, centered on the axis X302-X′302, of which the externallateral surface is hexagonal. The central protrusion 324 is hollow anddefines a tronconical receptacle 325 of which the diameter increases ina direction away from the plate 321, according to embodiments of thepresent invention.

As shown in FIGS. 11 and 12, the plate 321 has an elongated form, andextends the length of the lengthwise axis Y321-Y′321, perpendicular tothe axis X302-X′302. The central protrusion 324 is set backlongitudinally, along the axis Y321-Y′321 with respect to the center C21of the plate 321, according to embodiments of the present invention.

The articular body 302 is fabricated from one or two syntheticbiocompatible materials and adapted for partial or total articulation,such as for example polyethylene, PEEK, and/or polyurethane, accordingto embodiments of the present invention.

The central element 303 is substantially the same as central element303. Also, the central element 303 includes a tronconical intermediateportion 303.2 of which the diameter diminishes between the superior end333 and the inferior end 334 of the central element 303. One lateralexternal surface of the intermediate portion 303.2 includes aself-tapping threading and is traversed transversally by holes 338 whichare located at the base of the intermediate portion 303.3. Theintermediate portion 303.2 includes near its bottom an inferiortronconical portion 303.3, of which the cone shape includes a morepronounced slope than that of the intermediate portion 303.2. Theintermediate portion 303.2 includes near its top a superior tronconicalportion 303.2. A peripheral groove 337 is formed between theintermediate portion 303.2 and the superior portion 303.1, according toembodiments of the present invention.

The central element 303 is traversed by a longitudinal opening 332,which opens from one end of the central element 303 to the other andcommunicates with the holes 338. The opening 332 includes a superiorportion 332.1 of hexagonal cross-sectional shape, which opens onto thesuperior end 333, and an inferior portion 332.2 which is cylindrical andhas a circular cross-sectional shape and which connects the superiorportion 332.1 to the inferior end 334 of the central element 303,according to embodiments of the present invention.

The implantation of the glenoid implant 301 is similar to that describedfor implant 201, according to embodiments of the present invention. Thehexagonal shape of the central protrusion 324 permits the locking of therotation of the articular body 302 with respect to the glenoid.

Once the glenoid implant 301 is implanted, the bony tissue of theglenoid may recolonize the holes 338 and the opening 332, which helps toensure locking of the rotation of the central element 303 with respectto the glenoid, and improves the durability and the longevity of theglenoid implant 301, according to embodiments of the present invention.

The locking of the rotation of the central element 303 with respect tothe glenoid is achieved partially or exclusively by the middle of thearticular body 302, according to embodiments of the present invention.In fact, due to the hexagonal cross-section of the central protrusion324, the rotation of the articular body 302 with respect to the glenoidis locked. Taking into account the fact that the articular body 302 andthe central element 303 are each locked in rotation with respect to theglenoid, no other locking means are needed, according to embodiments ofthe present invention. However, according to some embodiments of thepresent invention, the locking between the articular body 302 and thecentral element 303 is achieved with a mortise-and-tenon joint.

The maximum transverse cross-sectional dimension of the central element303, taken perpendicularly to the longitudinal axis X303-X′303, issmaller than the transverse cross-sectional dimension of the plate 321of the articular body 302, taken perpendicularly to the longitudinalaxis X302-X′302. The contact between the central element 303 and thearticular body 302 is achieved solely on a portion of the articularbody, for example the central protrusion 324. The central element 33 isnot in contact with the entirety of the inferior surface 323, accordingto embodiments of the present invention. The central element 303 ensuresanchoring of the articular body 302 in the glenoid, and the inferiorsurface 323 of the plate 321 is not supported by the central element303, according to embodiments of the present invention.

FIGS. 13 and 14 illustrates an articular body 202 and central element203, according to embodiments of the present invention. The articularbody 302 is superimposed upon the articular body 202, and is representedin a position in which it is assembled with the central element 203,according to embodiments of the present invention.

The lateral separation of the central protrusion 324 with respect to thelengthwise axis Y321-Y′321 of the plate 321 is shown in FIGS. 11 and 12,in which a portion of the length 321.1 of the plate 321, located acrossfrom a plane P which is perpendicular to the axis X302-X′302, laterallyexceeds the articular body 202. A short portion 321.2 of the plate 321is located on the other side of the plane P. When the surgeon implantsthe glenoid implant 301 in the scapula, he positions the articular body301 in orienting the central protrusion 324 along the bottom, such thatwhen the patient lifts his arm, the humeral head has a tendency torotate the length portion 321.1 of the plate 321 towards the scapula, asshown by arrow F. The inferior face 323 of the long portion 321.1 is indirect contact with the glenoid, since the protrusion 324 is laterallyseparated, which permits the glenoid to receive directly the compressionforce which results from the tipping of the long portion 321.1,according to embodiments of the present invention.

FIGS. 15 and 16 illustrate a glenoid implant 401, according toembodiments of the present invention. The elements of glenoid implant401 which are similar to the elements of glenoid implant 1 have the samereference numbers, augmented by 100.

The glenoid implant 401 includes an articular body 402, similar or thesame as articular body 302, and a central element 403 of a “press fit”variety, for anchoring the articular body 402 in the glenoid of thescapula.

Also, the articular body 402, with a longitudinal axis X402-X′402,includes a plate 421, of which the superior face 422 includes anarticular surface for articulation of the scapula with the humeral head,according to embodiments of the present invention. An inferior surface423 of the plate 421 is provided with a central protrusion 424 having ahexagonal cross-sectional shape. The central protrusion 424 is hollowand defines a tronconical receptacle 425, of which the diameterdiminishes as it approaches the plate 421, according to embodiments ofthe present invention.

The articular body 402 is made from one or two synthetic biocompatiblematerials, such as, for example, polyethylene, PEEK, and/orpolyurethane, according to embodiments of the present invention.

The central element 403, with a longitudinal axis X403-X′403, includesan inferior portion 403.2 in the form of a prism with a hexagonal base.The central element 403 includes a superior end 433, and an inferior end434. The lateral stops of the central element are beveled progressivelyin the direction of the inferior end 434. The inferior portion 403.2 istraversed transversally by holes 438. The inferior portion 403.2 extendstowards the top along a superior portion 403.1. A peripheral groove 437is formed between the superior portion 403.1 and the inferior portion403.2, according to embodiments of the present invention.

The central element 403 is made from a metallic or biocompatible ceramicmaterial, such as a stainless steel, titanium, titanium alloy, and/orcarbon alloy, according to embodiments of the present invention.

The maximum transverse cross-sectional dimension of the central element403, taken perpendicularly to the longitudinal axis X403-X′403, issmaller than the transverse cross-sectional dimension of the plate 421of the articular body 302, taken perpendicularly to the longitudinalaxis X402-X′402. The contact between the central element 403 and thearticular body 402 occurs solely along a portion of the articular body402, for example along the central protrusion 424. The central element403 is not in contact with the totality of the inferior surface of theplate 421. The central element 403 ensures anchoring of the articularbody 402 in the glenoid, and the inferior surface 423 of the plate 421is not supported by the central element 403, according to embodiments ofthe present invention.

As the surgeon places the glenoid implant 401 in the glenoid, thesurgeon first forms a hole in the glenoid with dimensions slightlysmaller than those of the central element 403. Then, the surgeon impactsthe central element 403 to introduce it into the hole. The penetrationof the central element 403 in the glenoid is facilitated due to thelateral beveled stops. The rotation of the central element 403 withrespect to the glenoid is locked due to the hexagonal shape of thetransverse cross-section of the central element 403. The bonycolonization in the holes 438 may also contribute to locking therotation of the central element 403 with respect to the glenoid,according to embodiments of the present invention.

Next, the surgeon mounts the central protrusion 424 of the articularbody 402 on the superior portion 403.1 of the central element 403. Whenthe articular body 402 is assembled to the central element 403, thearticular body 402 is locked in translation and in rotation with respectto the central element 403, due to the fixation of the Morse cone typebetween these two elements. The axes X402-X′402 and X403-X′403 are thusaligned and coincident with the longitudinal axis X401-X′401 of theglenoid implant.

The rotational locking of the articular body 402 with respect to theglenoid is ensured by the hexagonal cross-sectional shape of the centralprotrusion 424, and by the friction between the superior portion 403.1of the central element 403 and the receptacle 425 of the centralprotrusion 424, according to embodiments of the present invention. Also,the glenoid implant 401 is locked in rotation, about the axisX401-X′401, with respect to the scapula, according to embodiments of thepresent invention.

FIGS. 17 and 18 illustrate a glenoid implant 501, according toembodiments of the present invention. The elements of glenoid implant501 which are similar to glenoid implant 1 include the same referencenumbers, augmented by 500.

The glenoid implant 501 includes an articular body 502, which may besimilar to or the same as the articular body 302, and a central element403 for anchoring the articular body 402 in the glenoid of the scapula,according to embodiments of the present invention.

The articular body 502 includes a plate 521 defined by a superiorconcave face 522, which includes an articular surface for articulationof the scapula with the humeral head, and by an inferior face 523,equipped with a central protrusion 524 that is cylindrical with acircular cross-sectional shape, according to embodiments of the presentinvention. The central protrusion 524 is hollow and defines atronconical receptacle 525 of which the diameter increases along adirection away from the plate 521, according to embodiments of thepresent invention.

The inferior side 523 includes a lateral post 526, parallel to thecentral protrusion 524, which includes a superior portion 526.1 which iscylindrical with a circular cross-section, of a diameter that is smallerthan the diameter of the central protrusion 524, which is connected tothe inferior side 523 of the plate 521, according to embodiments of thepresent invention. The lateral post 526 includes a tronconical inferiorportion 526.2, connected to the superior portion 526.1, of which thediameter increases in a direction away from the plate 521. The lateralinternal surface of the central protrusion 524 may be provided with aperipheral fin 527, according to embodiments of the present invention.

The central element 503 includes a tronconical intermediate portion503.2 of which the diameter decreases between a superior end 533 and aninferior end 534 of the central element 503, and which communicates withthe holes 538. An external lateral surface 531 of the intermediateportion 503.2 includes a self-tapping threading and is traversedtransversally by holes 538 which are located at the bottom of theintermediate portion 503.2, according to embodiments of the presentinvention. The intermediate portion 503.2 extends toward the base withan inferior tronconical portion 503.3, of which the conical shape has aslope that is higher than that of the intermediate portion 503.2. Theintermediate portion 503.2 extends toward the top with a superiortronconical portion 503.1, of which the larger diameter is across fromthe intermediate portion 503.2. A peripheral groove 537 is formed at theinterface between the superior portion 503.1 and the intermediateportion 503.2, according to embodiments of the present invention.

The central element 503 is traversed by a longitudinal opening 532,which opens toward both ends of the central element 503 and whichcommunicates with the holes 538. The opening 532 includes a superiorportion 532.1 of hexagonal transverse cross-sectional shape, which openson the superior end 533, and an inferior portion 532.2 which iscylindrical with a circular cross-sectional shape and which connects thesuperior portion 532.1 to the inferior end 534 of the central element503, according to embodiments of the present invention.

The maximum transverse cross-sectional dimension of the central element503 is smaller than the transverse cross-sectional dimension of theplate of the articular body 502. The contact between the central element503 and the articular body 502 occurs solely along a portion of thearticular body 502, for example at the central protrusion 524, accordingto embodiments of the present invention. The central element 503 is notin contact with the entirety of the inferior surface 523 of the plate521, according to embodiments of the present invention. The centralelement 503 ensures the anchoring of the articular body 502 in theglenoid, and the inferior surface 523 of the plate 521 is not supportedby the central element 503, according to embodiments of the presentinvention.

As the glenoid implant 501 is positioned in the glenoid, the surgeonfirst forms a hole in the glenoid with dimensions slightly smaller thanthose of the central element 503, according to embodiments of thepresent invention. The surgeon may also form in the glenoid a receptionhole for the lateral post 526. Then the surgeon inserts the centralelement 503 into the hole, using a tool equipped with a hexagonal tip,which may be inserted into the superior portion 532.1 of the opening 532of the central element 503, according to embodiments of the presentinvention.

Then, the surgeon inserts the articular body 502 onto the superiorportion 503.1 of the central element. The peripheral fin 527 positionsitself in the groove 537 of the central element 503, which serves tolock the translation of the articular body 502 with respect to thecentral element. The lateral post 526 serves to lock the rotation of thearticular body 502 with respect to the glenoid, according to embodimentsof the present invention.

Once the glenoid is implanted, the bony tissue of the glenoid mayrecolonize the holes 538 and the opening 532, which contributes tolocking the rotation of the central element 503 with respect to theglenoid and ameliorates the durability of the glenoid implant 501,according to embodiments of the present invention.

According to embodiments of the present invention, the central elements203, 303, 403, 503 are configured to receive any one of a metallic orceramic or synthetic articular body. In fact, the central element 203 ofthe glenoid implant 201 permits the fixation of a metallic or ceramicarticular body, by means of the superior portion 203.1 which forms ofcone of retention. In addition, the groove 237 of the central element203 serves to couple a synthetic articular body provided with aperipheral fin similar to fin 527 of the articular body 502, accordingto embodiments of the present invention. Also, the central elements 303,403 and 503 are provided, to the same end, with a tronconical portion303.1, 403.1, 503.1 adapted to be capped with a tronconical receptacle325, 425, 525 defined by an articular body that is metallic or ceramic,and by a groove 337, 437, 537 for coupling a synthetic articular body,according to embodiments of the present invention.

The threading of the tapped portion 32.2 may be replaced with groovesseparated along the length of the axis X3-X′3. Also, the number of fins25 may vary, according to embodiments of the present invention.

The articular body 2 may be formed of a metallic and/or ceramicmaterial, such as pyrocarbon. Such a material may be configured to notdeform, such that the fixation between the articular body 2 and thecentral element 3 is of a Morse cone type. Such fixation may replace thefins 25, according to embodiments of the present invention. PEEK mayinclude a remarkable rigidity for a polymer; as such, a Morse cone typeconnection may be used to fix an element formed of PEEK, according toembodiments of the present invention.

Moreover, the articular bodies 302, 402 may be formed of a hard metallicmaterial or a hard ceramic material, such as pyrocarbon, according toembodiments of the present invention.

According to an embodiment of the present invention, the superiorportion 32.1 of the opening 32 as well as the superior portion 24.1 aretronconical instead of cylindrical.

According to another embodiment of the present invention, the threadingof the lateral external surface 31 is to the left, while the threadingof the shaft 44 of the screw 4 is to the right. In such case, thethreading of the head 41 of the screw 4 is also to the right and thetapping of the inferior portion 32.4 of the opening is also to theright, according to embodiments of the present invention.

According to another embodiment of the present invention, the threadingof the lateral external surface 131 is to the left, while the threadingof shaft 144 of the screw 104 is to the right.

According to another embodiment of the present invention, the portion132.1 of the opening 132 is tronconical and the portion 132.2 iscylindrical, according to embodiments of the present invention.

According to another embodiment of the present invention, the screws 4and 104 are made of polymer, for example PEEK.

According to yet another embodiment of the present invention, theinferior portion 124.2 of the central protrusion 124 is cylindrical witha circular cross-sectional shape. In this case, the portion 132.2 isalso cylindrical with a circular cross-sectional shape and is adapted toreceive the inferior portion 124.2 of the central post 124, such thatthe fixation of the articular body 102 is achieved by inserting thecentral pin 124 into the central element 103 with force.

According to another embodiment of the present invention, the centralelement defines a receptacle for a central protrusion of an articularbody. For example, to be adapted to receive a synthetic articular body,the receptacle for a central element may include an internal threading,similar to the threading of the threaded portion 32.2 of the centralelement 32, into which the aforementioned fins clip along the length ofthe central protrusion, according to embodiments of the presentinvention. In order to be adapted to receive a metallic or ceramicarticular body, the central element may include a tronconical receptaclefor a central tronconical protrusion of the articular body, according toembodiments of the present invention.

The hexagonal portion 32.3 of the central element 3 and the blind hole42 of the head of the screw 4 may include a square cross-sectionalshape, for example in the form of a cross, a receptacle in the shape ofTorx®, or some other geometry permitting the use of a tool, according toembodiments of the present invention. Other embodiments may also includesuch features, for example the blind hole 142 of the screw 104 and thehexagonal portion 132.2 of the central element 103. Various tools withdifferent tips may be used depending on the types of screws or screwheads used.

The articular body 102 and 202 may be equipped with two supplementalinserts 105 received in the receptacles 121 a and 121 c or 221 a and 221c, according to embodiments of the present invention.

According to some embodiments of the present invention, a meanscomprised by the central fixation element for mechanically engaging withthe central protrusion may include, without limitation, elements 32.1and 32.2; elements 132.1 and 132.2; elements 203.1 and 237; elements303.1 and 337; elements 403.1 and 437; and elements 503.1 and 537.According to some embodiments of the present invention, a first meansfor locking rotation of the central fixation element with respect to theglenoid may include, without limitation, elements 31 and 4; 131 and 104;238; 338; 403.2 and 438; and 538. According to some embodiments of thepresent invention, a second means for locking rotation of the articularbody with respect to the glenoid may include, without limitation,elements 26; 106; 324; 424; and 526.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

What is claimed is:
 1. A glenoid implant for a shoulder prosthesis forimplantation in the glenoid of a scapula, the glenoid implantcomprising: an articular portion configured for articulation with ahumerus, the articular portion comprising a plate, the plate comprisinga side configured to be oriented toward the glenoid, the side comprisinga central element defining a recess extending between a first endlocated adjacent to the plate and a second end opposite the plate, therecess comprising: a proximal portion comprising a first threaded wallpattern, an intermediate portion comprising a non-threaded wall pattern;and a distal portion comprising a second threaded wall pattern; and adistal anchor screw comprising a proximal head and a stem extendingdistally from the proximal head, the proximal head being configured toengage the central element.
 2. The glenoid implant of claim 1, whereinwhen central element of the articular portion engages the proximal headof the distal anchor screw, at least a portion of the proximal head isdisposed in the intermediate portion of the central element.
 3. Theglenoid implant of claim 1, wherein the proximal head comprises anexternal surface comprising a third threaded pattern, and wherein thestem comprises an external surface comprising a fourth threaded pattern.4. The glenoid implant of claim 3, wherein the third threaded pattern isdifferent from the fourth threaded pattern.
 5. The glenoid implant ofclaim 1, further comprising a peripheral locking mechanism configured tolock rotation of the articular body with respect to the glenoid.
 6. Theglenoid implant of claim 5, wherein the peripheral locking mechanism isa lateral post extending from the side of the plate configured to beoriented toward the glenoid.
 7. The glenoid implant of claim 5, whereinthe peripheral locking mechanism comprises a receptacle configured toreceive a bone screw.
 8. A glenoid implant for a shoulder prosthesis forimplantation in the glenoid of a scapula, the glenoid implantcomprising: an articular portion configured for articulation with ahumerus, the articular portion comprising a plate, the plate comprisinga side configured to be oriented toward the glenoid, the side comprisinga central element defining a recess extending between a first endlocated adjacent to the plate and a second end opposite the plate, therecess comprising: a proximal portion comprising a first transversedimension, an intermediate portion comprising a second transversedimension that is different from the first transverse dimension; and adistal portion comprising a third transverse dimension that is differentfrom the first transverse dimension; and a distal anchor screwcomprising a proximal head and a stem extending distally from theproximal head, the proximal head being configured to engage the centralelement, the proximal head comprising an external surface comprising athreaded pattern, the stem comprising an external surface comprising adifferent threaded pattern, wherein the proximal portion of the recessfurther comprises a first threaded wall pattern, and wherein the distalportion of the recess further comprises a second threaded wall pattern,the second threaded wall pattern being spaced apart from the firstthreaded wall pattern by a non-threaded wall pattern.
 9. The glenoidimplant of claim 8, wherein when central element of the articularportion engages the proximal head of the distal anchor screw, at least aportion of the proximal head is disposed in the intermediate portion ofthe central element.
 10. The glenoid implant of claim 8, furthercomprising a peripheral locking mechanism configured to lock rotation ofthe articular body with respect to the glenoid.
 11. The glenoid implantof claim 10, wherein the peripheral locking mechanism is a lateral postextending from the side of the plate configured to be oriented towardthe glenoid.
 12. The glenoid implant of claim 10, wherein the peripherallocking mechanism comprises a receptacle configured to receive a bonescrew.